Originally Posted by Steve_ZA

Assuming that you are arriving at JFK T8 from LHR (rather than DUB which starts again in April I think) there are no shortcuts without Global Entry/TSA Pre. Immigration -> Land side -> Security -> (Lounge - up the stairs/elevator on your left after security) -> Gate.

On the return to T8 follow signs for baggage reclaim/exit - this is down the escalator to the right of the TSA security checkpoint you came through on arrival, once outside the baggage reclaim area turn left and use one of the elevators to go up to the Air Train. Take the Air Train one stop over to T7 (make sure you get the one for "All Airline Terminals") you need to cross the road to enter T7 and then keep left for the "Fast Track", which may or may not be fast on the day.